Depends on the guitar. My friend has a really sweet sounding guitar with a amazing sounding condenser pickup built in. It sounds great both through a DI and mic'd.
But most of the time micing is the only way to go.
Try both, see what works for that guitar, player and type of music. In heavier rock music you can get away with thin sounding accusitc guitars, but if its solo you really need a nice warm full bodied sound which you can only get by mixing mic and DI or two mics. One on the body and one on the neck works well, try many diffrent placements and mics.